Electromagnetic devices, such as inductors, transformers and similar devices include magnetic cores in which a magnetic flux flow may be generated in response to an electrical current flowing through a conductor winding associated with the magnetic core. As current (AC) in the magnetic core increases, the inductance in the core increases (energy storage in the device increases). In a transformer configuration which includes a primary winding connected to an electrical power source and a secondary winding connected to a load, changes in the current or voltage supplied by the electrical power source can significantly change the energy being stored in the magnetic core for transfer into the secondary. For example a lightning strike on the primary winding of the transformer can result in extremely high voltage and current levels transferred to the secondary which may potentially damaging to the load. Accordingly, there is a need to control a level of magnetic flux flow in the cores of transformers and other electromagnetic devices.